Tray with flat bottom reference surface

ABSTRACT

A molded component tray includes a component housing portion having a plurality of component pockets. The tray has a flange around the component housing portion defining a perimeter of the tray. A flange top surface in one embodiment is below the component housing top surface. A flange bottom surface includes recessed areas positioned in alignment with mold ejector pins which may contact the flange bottom surface, and alternatively in alignment with mold ejector pin marks on the flange top surface. The depth of the recesses is greater than the height burrs left by the ejector pins, thereby leaving the tray bottom surface free of burrs caused by ejector pins. Alternatively, when one tray is stacked on top of another, the recesses in the bottom of an upper tray can be positioned to allow clearance for ejector pin marks on the top of the flange of a lower tray.

RELATED APPLICATIONS

This application is related to U.S. Application entitled Bare Die TrayWith Flat Datum Surface filed on the same date as this application,bearing attorney reference 0678100301344 which is expressly incorporatedby reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to trays for use in carrying components such assemiconductors, and more particularly to a tray having flat datumsurfaces and configured to avoid calibration variations due to moldinjector pin burrs imposed on the tray during manufacture.

2. Description of the Related Art

Small components such as semiconductors are often stored or shipped inmolded plastic trays similar to tray 10 shown in FIGS. 1A and 1B. In themolding production operation, ejector pins are used to push/eject thetray from the mold casing. Burrs are caused from molten plastic fillingthe circumferential gap between the ejector pin and the ejector pinhole. Slight protrusions can also occur if the ejector pin is not levelwith the part surface. Part ejection is a forceful process, and thepressure of the pins on the tray leaves burrs/marks/blemishes on thetray surfaces. These burrs cause variations in the effective traythickness and as a result trays cannot be stacked with a consistentheight or degree of flatness. The burrs cause errors in calibration ofautomated tray handling equipment, and equipment for picking and placingcomponents in tray component pockets. Removal of burrs would involveadditional and expensive machining or manual processes, and generally isnot practical.

FIG. 1A is a perspective top view of a prior art tray 10 showing ejectorpin marks/burrs 12 left after ejecting the tray 10 from a mold. FIG. 1Bis a perspective bottom view of the tray 10 showing ejector pin marks14. For stacking of trays such as tray 10 and for calibration ofautomated tray handling equipment for use in handling trays of thedesign shown on FIGS. 1A and 1B, it is necessary to use surfaces 16 and18 as reference surfaces. The burrs 12 and 14 cause problems in thecalibration. For example, since the burrs are not consistent from onetray to another, the height of surface 20 is less certain from one trayto another, and from one side of a tray 10 to another side of the tray.These distorted/inaccurate reference surfaces limit the ability ofautomatic machines to accurately pick and place components in the tray.The burrs 12 and 14 also cause an uncertainty in the height andstraightness of a stack of trays 10, causing problems with automaticstack handling equipment, as well as problems with shipping containersand clips.

SUMMARY

It is an advantage of this invention in that it provides a componenttray that has improved reference surfaces.

It is a further advantage in this invention in that it adds recessedareas for contact with mold ejector pins so as to avoid uncertaincontacts due to burrs, and therefore provides a flat datum surface.

It is a still further advantage of this invention in providing a traythat in use maximizes the accuracy of calibration of automatedequipment.

It is another advantage of this invention in providing a tray that canbe stacked accurately.

It is another advantage of this invention in providing a tray whereinejector pin blemishes do not affect stacking of trays and calibration.

In one embodiment of the present invention, a molded component trayincludes a component housing portion having a plurality of componentpockets. The tray has a flange around the component housing portiondefining a perimeter of the tray. A flange top surface in one embodimentis below the component housing top surface. A flange bottom surfaceincludes recessed areas positioned in alignment with mold ejector pinswhich may contact the flange bottom surface, and alternatively inalignment with mold ejector pin marks on the flange top surface. Thedepth of the recesses is greater than the height of burrs left by theejector pins, thereby leaving the tray bottom surface free of burrscaused by ejector pins. Alternatively, when one tray is stacked on topof another, the recesses in the bottom of an upper tray can bepositioned to allow clearance for ejector pin marks on the top of theflange of a lower tray.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective top view of a prior art tray;

FIG. 1B is a perspective bottom view of the prior art tray of FIG. 1A.;

FIG. 2A is a perspective top view of a tray according to the presentinvention;

FIG. 2B is a perspective bottom view of the tray of FIG. 2A according tothe present invention;

FIG. 2C is an enlargened section view from FIG. 2B;

FIG. 3 shows two trays stacked, with recesses in the tray bottom flangesurface; and

FIG. 4 shows two trays stacked, with recesses in the flange top surface.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the present invention will be described herein with reference toparticular embodiments thereof, a latitude of modifications, variouschanges and substitutions are intended, and it will be appreciated thatin some instances some features of the invention will be employedwithout a corresponding use of other features without departing from thespirit and scope of the invention as described with respect to thepreferred embodiments set forth herein.

Referring now to FIGS. 2A and 2B, a component tray 22 is shown that hasbeen formed in a mold. The tray 22 has a component housing portion 24,containing a plurality of component pockets 26 opening to top surface28. The component pockets 26 are for holding small components, such assemiconductor devices. A flange 30 extends around the housing portion24, defining the perimeter of the tray 22. The flange 30 has a flangetop surface 32, and a bottom surface 34 shown in FIG. 2B. The flangealternatively can be of other configurations, for example the flangecould extend less than completely around the housing, or could be insegments, such as only on two opposite sides of the housing. The flangetop surface 32 can alternatively also be of different heights, includingabove, below or equal to the top surface 28 of the housing 24. FIG. 2Ashows burrs/blemishes 36, which may or may not occur on the surface 32.The burrs/blemishes 36 shown in FIG. 2A raised from the top surface 32may be due to mold ejector pins when the molded tray 22 is ejected fromthe mold. FIG. 2B is a bottom perspective view of the tray 22 of FIG.2A, and also shows burrs/blemishes 38 formed as a result of pressure ofmold ejector pins.

According to the present invention, recesses 40 are formed along thebottom surface 34 to be in alignment with the burrs/blemishes 36 and/or38, which in a particular embodiment are caused by ejector pins used forremoving the tray from a mold. For example, if the mold is designed forejector pins to push on the bottom of a tray for the purpose of ejectingthe tray from the mold, the recesses are configured to be in alignmentwith the ejector pins and at a diameter somewhat greater than the pinsso that the pins make their mark on the bottom of the recesses 40. Thedepth of the recess need only be in excess of the height of theburr/mark 38 left by the ejector pins.

In the event that burrs exist on the top surface 32, such as ejectorpins used to press on the top surface 32 of the tray, then the recesses40 in the bottom surface are designed to provide corresponding clearancefor the burrs 36 on the top surface, so as to allow a flat matingsurface 32 for a tray bottom surface 34 in the event that the trays arestacked.

A recess 40 can therefor provide a recess bottom surface upon which toapply an ejector pin, or/and the recess 40 can serve to provideclearance for a burr/mark on a mating top surface when trays arestacked.

FIG. 2C is an enlargened section A taken from FIG. 2B to show recessesand burrs more clearly.

The recesses 40 of FIG. 2B are shown as an example of the concept of thepresent invention. The invention also includes recesses of otherconfigurations and positions to allow clearance for burrs/blemishes inany mating surface that the tray may be set upon. For example, in theevent that trays are stacked, a recess in surface 34 may be included toallow clearance for any raised mark in the surface 32 of a lower tray. Araised mark for example, could be caused by an ejector pin, or it couldfor example be a company symbol/logo or a part number, etc.

As a further alternate embodiment, one or more recesses can be placed inthe top surface 32, to provide recess bottom surfaces for ejector pinsthat may be applied to the top surface 32, or as a recess to provideclearance for an ejector pin mark on a tray bottom surface when traysare stacked. It should be noted however, that placing a recess only onthe top surface does not provide a flat reference surface on the bottomof a tray, which would be a problem for the bottom tray of a stack ifthere are marks on the bottom surface.

FIG. 3 is a cross sectional view of two trays 42 and 44 stacked one uponthe other, and illustrates the use of recesses 46 to achieve a flatbottom reference surface 48, for example on tray 42 to sit on the topsurface 50 of tray 44, and the flat bottom surface 48 on tray 44 to siton a base surface 54. FIG. 3 shows how the recesses 46 provide clearancefor burrs 56 on the top surface 50 of tray 44, as well as provide recessbottom surfaces 58 for the application where contact with ejector pinscauses burrs 60.

FIG. 4 shows two trays 62 and 64 stacked, wherein the trays haverecesses 66 in the top flange surface 68 to provide a recess bottomsurface 70 for receiving ejector pins that leave a mark/burr 72.

The present invention also includes trays with recesses in both the topand bottom surfaces for providing clearance for any type of surfaceburrs/blemishes, such as ejector pin marks or raised lettering, logos,etc. in a mating surface.

While the present invention has been described herein with reference toparticular embodiments thereof, a latitude of modifications, variouschanges and substitutions are intended in the foregoing disclosure, andit will be appreciated that in some instances some features of theinvention will be employed without a corresponding use of other featureswithout departing from the spirit and scope of the invention as setforth in the appended claims.

1. A tray comprising: a molded tray including a component housing havinga plurality of pockets for holding components; and a tray surface havinga plurality of recesses, each recess for recessing a burr on a bottomsurface of said recess below said tray surface.
 2. A tray as recited inclaim 1 wherein said burr is caused by contact of a mold ejector pinwith said bottom surface.
 3. A tray as recited in claim 1 wherein saidtray has a flange, and said tray surface includes a flange surface.
 4. Atray as recited in claim 3 wherein said tray surface includes a flangetop surface.
 5. A tray as recited in claim 3 wherein said tray surfaceincludes a flange bottom surface.
 6. A tray comprising: a tray forholding a plurality of semiconductor devices, said tray including acomponent housing having a plurality of pockets for holding saidsemiconductor devices; and a flange surrounding said housing, saidflange having a flange surface with a plurality of recesses formedtherein for providing clearance for a burr on a mating surface forcontacting said flange surface.
 7. A tray as recited in claim 6 whereinsaid flange surface is a flange bottom surface, and said mating surfaceis a flange top surface of a second tray upon which said tray is to beplaced.
 8. A tray as recited in claim 7 wherein said burr is caused bycontact of a mold ejector pin with said flange top surface of saidsecond tray.
 9. A method of tray manufacture comprising: forming aplurality of recesses in a tray for holding semiconductors devices usinga mold; and applying a mold ejector pin to a recess bottom surface of asaid recess for ejecting said tray from said mold.
 10. A method asrecited in claim 9 wherein said tray includes a flange, and at least oneof said recesses is in a flange top surface.
 11. A method as recited inclaim 10 wherein said tray includes a flange, and at least one of saidrecesses is in a flange bottom surface.